This invention relates in general to optical devices, and more particularly, to optical imaging systems.
The use of multi-spectral systems is becoming more common with the development of new focal plane arrays.
One such application is the ability to see the laser spot of a laser while imaging in the mid-wave infrared band. This “see-spot” capability is extremely useful for bore-sighting a laser to an imaging system. By enabling the “see-spot” in the infrared, bore-sighting is possible both at night and during the day.
Multi-spectral designs are often limited to all reflective designs because of axial chromatic aberration. All-reflective designs may contain off-axis mirrors, taking up a large volume and providing difficult tolerances. This would make it extremely risky to build a production type system that fits into a small volume.